1. Field of the Invention
This invention relates to a resin composition, and more particularly to a polyolefin resin type resin composition enhanced in impact resistance while retaining its characteristic properties such as stiffness, etc.
2. Description of the Prior Art
Polyolefin resins and particularly crystalline polyolefin resins are characterized by low density and inexpensiveness in addition to their excellent properties such as stiffness, electrical properties, solvent resistance, moldability, processability, etc. and therefore extensively used practically in the form of various molded articles and films.
However, such polyolefin resins still have some faults, and their improvement in these points is waited for. One of the faults is inferiority in impact resistance. A variety of proposals have hitherto been made for the purpose of overcoming this fault. Such proposed methods include, for example, a method of blending an elastomer into a polyolefin resin, a method of forming a random or block copolymer having an elastomeric constituent made of plural olefin monomer units in a polyolefin resin by polymerization with the aim of improvement (Japanese Patent Application Kokai (Laid-Open) No. 63-30950), etc.
On the other hand, there have been made various attempts to blend a polyolefin resin with other thermoplastic resin for the purpose of producing a material improved in heat resistance of which inferiority is another fault of Polyolefin resin, while retaining the above-mentioned excellent characteristic properties of polyolefin resin such as moldability, etc. Thus, a resin composition comprising a polyolefin resin and a polyphenylene ether resin [Japanese Patent Application Kokoku (Post-Exam.) No. 42-7069, Japanese Patent Application Kokai (Laid-Open) No. 2-115248, etc.], a resin composition comprising a polyolefin resin and a polyphenylene sulfide (Japanese Patent No. 1,005,081), a resin composition comprising polystyrene and polypropylene (U.S. Pat. No. 4,237,190), etc. have already been proposed.
However, these methods and compositions having been proposed up to today all have some faults and cannot be satisfactory from the industrial point of view. That is, in the above-mentioned methods for improving impact property of polyolefin resin by blending an elastomer into it or modifying a polyolefin resin by polymerization, a practically improved impact property can be acquired only when a considerably large quantity of elastomer is made to exist in the polyolefin resin, as the result of which the original excellent properties inherent in polyolefin resins such as stiffness, heat distortion resistance, etc. are inevitably deteriorated.
In composition comprising a polyolefin resin and other thermoplastic resin, a resin composition excellent in compatibility is generally difficult to obtain because of the low affinity between polyolefin resin and other thermoplastic resin, and it is yet impossible to obtain at the present state to prepare a resin composition comprising a polyolefin resin and other thermoplastic resin having so excellent properties as to be fit for practical uses, in spite of the many proposals. There have been made various proposals regarding improvement of compatibility in the compositions comprising a polyolefin resin and other thermoplastic resin. For example, regarding the compositions comprising a polyolefin resin and a polyphenylene ether resin, a resin composition comprising an acid-modified polyolefin resin and a polyphenylene ether resin (Japanese Patent Application Kokai (Laid-Open) No. 60-120748), a resin composition comprising a modified polyolefin resin, a modified polyphenylene ether resin and a binder (Japanese Patent Application Kokai (Laid Open) No. 63-128056, a resin composition prepared by compounding an amino group-containing modified polyolefin resin, a polar group-containing modified polyphenylene ether resin, a polyolefin resin, a polyphenylene ether resin, etc. (Japanese Patent Application Kokai (Ladi-Open) No. 2-173137 ), etc. have been proposed. However, these proposed resin compositions are insufficient in compatibility and unsatisfactory in mechanical properties and particularly in impact resistance and tensile elongation, though they are improved in solvent resistance, moldability, etc.
Regarding the improvement of a resin composition comprising a polyolefin resin and a polyarylene sulfide resin, a resin composition comprising an olefin copolymer and polyphenylene sulfide (Japanese Patent Application Kokai (Laid-Open) No. 58-154757), a resin composition comprising a modified polyolefin resin, polyphenylene sulfide and an epoxy resin [Japanese Patent Application Kokai (Laid-Open) No. 59-207921], etc. have been proposed. Further, regarding the improvement of a resin composition comprising a polyolefin resin and a polystyrene type resin, a resin composition containing a hydrogenated block copolymer as a third ingredient [Japanese Patent Application Kokoku (Post-Exam.) No. 62-34782 and Japanese Patent Application Kokai (Laid-Open) No. 1-174550], etc. have been proposed. However, these Proposed resin compositions are yet insufficient in impact resistance.